1. Field of the Invention
This invention relates to a tube like applicator for liquid dispensing from a self contained crushable liquid filled ampule which is activated by a rotatable slide ring.
2. Description of the Prior Art
Applicators for dispensing liquids for various uses and which are primarily of the single use throw away type are known in the art. Such applicators take many forms, but the common factor is that a thin walled glass ampule is provided to contain the liquid, which is then encased in an outer casing, which can be a cardboard or plastic tube, the ampule is crushed for use by squeezing it between the fingers of the user or by an external lever. There are many considerations that must go into the design of liquid applicators. They must be easy to activate, the glass must be contained in the tube after breakage, the cost must be minimal, and the device must be easy to use.
Devices that utilize a lever positioned near the dispensing end of the applicator are known. The sealing of the glass ampules and the geometry of the sealed ends causes the ends of the ampules to be thicker than the walls, which results in greater forces required to break the ampules. When the contents of the ampule are above 2-3 milliliters the wall thickness is increased considerably, and the force required to crush it is greater since the effort required to break the ampule wall increases exponentially as the thickness of the wall increases. In ampules with contents above 2-3 milliliters, the wall thickness must be increased to maintain the integrity of the ampule.
The U.S. Patents to Avery U.S. Pat. Nos. 3,891,331 and 4,183,684 discuss some of the problems associated with larger ampoules, which they do not solve. The U.S. Patent to Arcudi U.S. Pat. No. 3,466,131 is also pertinent, but the ampoule cannot be broken between the fingers in the larger ampoule sizes.
The 3M COMPANY provides a Duraprep applicator which utilizes a "lever" to break the glass ampoule, but is subject to the same problems, i.e. as a larger fill is required, a thicker ampoule is required which in turn requires larger forces to crush.
The lever type of ampule activator requires considerable force as it only applies force to one side of the ampule, and the wall thickness of the surrounding container accordingly must be increased to accommodate the larger size and quantity of glass particles produced by activation.
The slide ring applicator of the invention is located at the thinnest portion of the ampule, and provides a one hand operation where force is applied inwardly to both sides of the ampule by twisting the slide ring, which structure obviates the problems posed by the prior art devices and provides many positive advantages.